In the art of multiple discs brake units which mount on an end bearing bracket of an electric motor for braking a projecting end portion of the motor shaft, for example as disclosed in U.S. Pat. Nos. 2,025,098, 2,964,137 and 3,680,666, it has been found desireable to use a liquid coolant or oil within the brake unit for dissipating the friction heat produced when the brake discs and brake plates are clamped together. For example, the above-mentioned U.S. Pat. No. 3,680,666 discloses two motor brake units each of which includes a housing enclosing a supply of cooling fluid or oil which is used for transferring heat. U.S. Pat. Nos. 3,638,773 and No. 3,924,715, which issued to Applicant's Assignee, disclose clutch-brake units of the oil-shear type and wherein a cooling oil is recirculated to provide for dissipating friction heat in addition to providing a lubricating fluid to extend the operational life of the unit.
In a motor brake unit of the general type disclosed in above mentioned U.S. Pat. No. 3,680,666, it has been found highly desirable to provide for effective and positive recirculation of the oil within the brake unit to prevent localized or spot heating of the brake discs and plates and also to provide for effective cooling of the oil as the oil is being recirculated. It is also desirable for the oil recirculating system to be an integral part of the motor brake unit in order to avoid the need for an auxiliary oil pump system.
While a positive or effective recirculation of the cooling oil significantly extends the operational life of the brake discs and plates, it is still sometimes necessary to replace the brake discs and plates after an extended period of use. Thus, it is also desirable for the motor brake unit to be constructed for conveniently and quickly replacing the brake discs and plates without requiring substantial disassembly of the motor brake unit. For example, in order to replace the brake discs and plates within either of the motor brake units disclosed in the above mentioned U.S. Pat. No. 3,680,666, it is necessary to disassemble the bearing which supports the outer end portion of the sleeve mounted on the motor shaft or to provide for pulling the sleeve from the motor shaft using the center hole within the sleeve. These brake units also do not provide for any positive or effective recirculation of the cooling oil outwardly between the brake discs and plates during operation of the brake unit.